This book is the result of having searched and investigated in the sacred books of the most popular religions and philosophies, the common and most important points that unite all of them. Trying to order and explain these main ideas in a logical and practical way, and to purge them of the particular dogma of each school, using a simple vocabulary, and without the need to have previous experience in any type of reading, it makes it light but deep at the same time, leading us to personal introspection and meditation, which is the main objective of the book.